Employment of cement and the like



106. COMPOSITIONS, an

COATING OR PLASTIC.

h r I Patented Sept. 29, 19 31 7 UNITED STATES PATENT OFFICE GERALD NOEL WHITE, OF LONDON, ENGLAND, ASSIGNOR OF ONE-HALF TO SCOTTISH DYE-S, LIMITED, OF GRANGEMOUTH, SCOTLAND EMPLOYMENT F CEMENT AND THE LIKE No Drawing. Application filed November 3, 1927, Serial No. 230,931, and in Great Britain November 10, 1926.

This invention relates to the treatment (b) In place of ammonium carbonate or of cement in connection with building mate other soluble treating materia lightly solurials. ble or even insoluble bodies may be em- The principal or first matter with which ployed (such as an insoluble acid salt of it deals is the prevention of incrustation on calcium) for example, or calcium h dro en cement and other building materials. hos hates for the purpming- In carrying out my researches mainly the calclum hydroxide and yielding subfrom that aspect, however, I have arrived stantially insoluble compounds. at other important applications of some or (0) Among the carbonatation preventing 10 all of the materials which may be used for agents which may be used specific mention the prevention of incrustation as aforesaid. is made in addition to those given above I will first deal with the matter of of ammonium phosphate, am-

crustation. ,momuni meta hos hate ammonlum ro- It is well known that on exposure to the am mnmmgf 'fi 15 atmosphere structures or other articles made E ammonium bicarbonate. 5 wholly or partly of cement and other buildi iere co oration comes into question in materials contamm such colours as vat dyestufls in the form of larly those that contain free l1me, tend to fine pastes as usually supplied for printing, devemp IIICIIISWIOIITYDB phenomenon befor instance Caledon jade green, or Caledon g0 ing generally referred to as carbonatation brilliant purple RR, Caledon red BN, 7 1

or laitance. Whilst in some cases this Caledon blue BC or the like in similar or occurrence may not be considered as particother suitable form or mineral colours, for ularly objectionable, there are other cases instance iron oxide or chrome green, may in which such incrust-ations are undesirable, be employed.

[.5 and this is particularly so in the case of My continued researches in the use of amcement or other building material which monium carbonate have led to increased has been coloured, e. g., by mineral oxidesutility of this substance and in order that or by vat dyestuffs according to the procthe matter may be well understood I set esses described in British specifications Nos. out below what I have found to be a con- 3g 6,479/26, 18,168/26 and 20,368/26 as the carvenient theory whether in fact this be the bonatation causes a lightening effect or obtrue explanation of the actions which ocscuring of the colour either uniformly over our or not.

- the whole surface, or in patches. I have found that such an addition for The principal object of the invention is example from about 25 per cent. to 50 per 35 to provide for the overcoming of this difcent. by weight of dry commercial ammofi lty nium carbonate calculated on the we To that end I have made researches and cry cemen use improves the permanence I have found that carbonatation, which is against cracking of cement washes. The due to the superficial formation of calcium permanence of such washes is largely inde- 40 carbonate, can be wholly or partially prependent of the age of the surface to which vented or retarded by the addition to the it is applied. The method of procedure may building material of a substance preferg bly consist of mixing the cement with an equal readil soluble in water czTEiiiliiiffdfm Weight of saturated ammonium carbonate a hlg ly lnsolubleproduct with: lime, For solution and applying it to the surface im- 45 this purpose I prefer to use ammonium carmediately. A preferred method of probonate. cedure is to apply to the surface a wash con- Further I have found that sisting only of cement gauged with water (a) If it be desired to make an addition and immediately after to apply ammonium substantially before use horax or the like carbonate in the form of a saturated solumay be employed. tion by means of a brush, such cement i l l y l i washes setting within a few minutes andgwr a material slightly continue setting until a durable surface is so u e or even insoluble, for example an obtained.

insoluble salt of calcium, such as calciuip In gauging cement with water containing hvdro en hos hate for the purpose a quantity of ammonium carbonate between mm. m tfi Tficium hydroxide and 3 per cent. and 5 per cent. of the weight of the cement, the amount of ammonlum carbonate is sufficient to react with only some 8 per cent. to 16 per cent. of the free lime 10 present in the set cement leaving out of the question the reaction between ammonium carbonate and the calcium silicates and other calcium compounds. Precaution should be taken to provide that the ammonium carbonate is equally distributed. so far as practical conditions will allow throughout the whole of the concrete mass and that local excesses of ammonium carbonate are not allowed to exist more than 2 momentarily. In practice this condition can be satisfied by thoroughly incorporating the bulk of the gauging water with the cement, leaving the addition of ammonium carbonate in the form of a saturated solution to the end, mixing it in rapidly and efficiently.

In the case of cement and ammonium carbonate mixtures containing high proportions of ammonium carbonate, the first set normally occurs within a few minutes and 80 if this first set be disturbed or the mixture is not applied sufficiently quickly it may fail to set. If undisturbed the mass sets and begomes hard during the course of a few It is desirable in the case of washes to apply the cement wash gauged only with water and to carry out the admixture of ammonium carbonate by application in situ, mixing the ammonium carbonate in by means of a brush.

The effect on the setting properties of the cement of even small proportions, e. g., 5 per cent. of ammonium carbonate calculated on the weight of cement, is clearly noticeable, but in this case it only amounts to an increase in the setting time however prolonged is the process of application. It appears that the final strength of the cement or concrete is slightly raised which I regard as evidence that there occurs formation of a colloidal envelope round the cement particles, which, by gradual crystallization, be-

comes equivalent to a cement ground to a limiting fineness.

My invention consists in a method for the prevention or retardation of incrustation on cement or other building materials which comprises the incorporation therewith of a substance preferably readily soluble in water which will react with the lime to form a substantially insoluble compound or compounds, for example ammonium carbonate,

boric ac' ammonium meta l'ios hate 5 1- e yielding substantially insoluble compounds.

The invention also consists in a method for the treatment of cement which comprises the incorporation therewith at a suitable stage and in a suitable form of an appropriate quantity of a protective agent, for example the employment in cement washes of about 25 per cent. to 50 per cent. by weight of dry commercial ammonium carbonate.

The invention also consists in a method of treating a building surface or the like which comprises the application to the surface of a wash consisting of cement or cementitious material gauged with water and the subsequent application 0 ammonium. carbonate in the form of a substantially saturated solution.

The invention further consists in the employment of colours in conjunction with the treating agents referred to in the preceding three paragraphs.

The following examples illustrate how the invention may be carried into effect, all parts being parts by weight Example 1 This is an example dealing more particularly with resistance to cracking of cement washings and renderings.

100 parts of cement are gauged with 50 parts of water and the resulting slurry is applied to any desired surface previously wetted with water. As soon as the cement wash has been applied the whole is sprayed with a saturated solution of ammonium carbonate which is worked in and distributed rapidly by means of a brush.

Example 3 This is a modification of Example 2.

Concrete which has been recently made, and preferably in the condition of its first set, is treated with' a saturated solution of ammonium carbonate applied by any suitmonium ios a e ammonium vro 10S- able means and worked in rapidly with a P5 gliate, urea, ammonium carfiamate and ambrush.

I06. COMPOSITIONS,

COATING OR PLASTIC.

Ewamle 4 This is a modification of Example 1 employing ammonium phosphate.

According to this example in place of ammonium carbonate used in Example 1 there is employed for reaction with the lime an equivalent amount of (Ii-hydrogen sodium phosphate.

E wample 5 This is an example of the employment of ammonium carbonate in conjunction with a vat dyestufl, namely Caledon jade green.

2.5 parts of Caledon jade green standard paste as usually supplied to the calico printing trade and 2.5 parts of ammonium carbonate are mixed together and added to the gauging water for 100 parts of Portland cement and 200 parts of sand or other aggregate.

A larger quantity of Caledon jade green may be used, for example 7 .5 parts instead of 2.5.

Example 6 This is a modification of Example 5 in which Caledon brilliant purple is used.

10 parts of Caledon brilliant purple RR in the form of a fine paste as usually supplied for printing and 5 parts of ammonium carbonate are added to the gauging water for 100 parts of cement and 300 parts of marble chips or other aggregate.

General For the purpose of preventing or retarding carbonatation there may be employed among others any soluble substance which will react with lime to precipitate or form an insoluble compound but the material or materials selected should have the minimum (if any) adverse effect on the strength or other desired properties of the cement and the minimum liability to increase the formation of such soluble incrustations as are known as efilorescence. As stated I prefer for this purpose to employ an ammonium compound especially ammonium carbonate.

The term ammonium carbonate as used herein includes the commercial material of that name and it is to this substance that the specific examples apply by way of illustration. This may be prepared for instance by subliming chalk with ammonium chloride or sulphate, and which is believed to consist of a mixture of ammonium carbamate and ammonium bicarbonate.

It is generally unnecessary to use that amount of ammonium carbonate or other reagent which is requisite to react with the whole of the free lime which is present in or may be formed during the setting and hydration of the cement, it being suflicient to add such a quantity as will suflice to retard seepage of lime in solution to the surface of the building material. In the case of cement about 1- per cent. to about 10 per cent. of commercial ammonium carbonate, calculated upon the weight of the cement is usually required although the amount may vary according to the nature and composition of the building materials.

In place of adding the ammonium carbonate or other precipitant in the form of a solution by itself it may be added in admixture with any preparation to be used for colouring the cement or building material. If desired the precipitant may be added in the dry state. If ammonium carbonate be chosen as the precipitant, it should be added shortly before the use of the cement. If it be desired to make an addition substantially before use, borax or the like may be employed.

The precipitant added in the drv state should be thoroughly mixed with the dry cement or with the aggregates or with both. Any other suitable means for adding the reagent may be employed and if desired a plurality of suitable precipitating agents may be used.

As shown by some of the examples given above colouring material can be employed and this may be added either to the cement or to the ammonium'carbonate or the like as preferred. Any suitable colouring material may be employed for instance vat dyestuffs or colouring matters such as anthraquinone vat dyestuffs or colouring matters,

e. g., Caledon jade green. Caledon brilliant purple RR, Caledon red BN, Caledon blue BC in the form of fine pastes as normally supplied for printing and the corresponding dyestuffs sold under other trade descriptions or mineral colours, e. g., or chrome green.

TVhen ammonium carbonate is used in conjunction with vat dye-stuff pastes the dyestuif appears to be carried down by the colloidal precipitate and become a part of the envelope surrounding the cement particles.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is The method of settling the color and arresting incrustation on the exposed surfaces of set cemeutitious material which comprises incorporating 3 to 5% of commercial ammonia carbonate with a cement containing free lime and vat dye stuff colors reacting to form a colloidal precipitate binding the color.

In testimony whereof I have signed my name to this specification.

GERALD NOEL TVHITE.

iron oxide 

